Kamsi
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A 57 yr old man is noticed on pre-employment physicial to have"moon facies" with a "buffalo hump".Muscle wasting and abd striae .The man is referred to an int med specialist for further evaluation.Early morning plasma cortisol is 35mg/dl.A screening dexa suppression test is then orderedin which 1mg is given orally at11.30pm.The following morn at7amplasma cortisol is 6mg/dl.No dexa is given for 1 wk.Then a repeat study is performed with oral dexa 0.5mg 6hris given for 2 days,Urinary free cortisol on the 2nd day is 30mg/24hr.The oral dose of dexa is then inceased to 2mg 6hr for 2 days and urin ecortisol is 10mg/24hr on the 4th day.These findings are consistent with
A Exogenous cortisol administration
B Hypersecretion of ACTH by an adrenal tumour
C Hypersecretion of ACTH by pituitary gland
D.Hypersecretion of ACTH by a small cell CA
E Hypersecretion of cortisol by an adrenal tumour
Pls explain how to interprete the findings of the suppression tests in the different disease condtions
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| Justice
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C Hypersecretion of ACTH by pituitary gland
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| dr in trouble
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C
Dexa suppression test (High dose)--if cortisol levels suppress---Pituitary gland
If not suppress---Ectopic production of ACTH or Adrenal gland adenoma----measure ACTH levels----if high then ectopic production if low then Adrenal Adenoma.
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| hgheith
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Dexa is a cortisol analogue that acts on pituitary
The way it's done: first there is the low dose test: which is the overnight dexa.
normal test = no prob.
abnormal test = then test the 24 hour urnie for cortisol (can have falst + with the overnight test) if it's negative = No cushings
positive= cushing syndrome now find out if it's pituitary or other -- you do the HIGH dose dexa test
if cortisol is suppressed = it's Pituitary (cushings dz) and you tx with surgery.
If there is no response to the high dose that means you could not suppress the release of cortisol which means that there is no feedback inhibition so it has to be a tumor acting on it's own. (there is feedback inhibition with ACTH and cortisol, if cortisol is high then ACTH should be low and viseversa)
SO if you could not suppress cortisol
= ACTH producing tmor or Adrenal neoplasia.
ONE MORE test
ACTH level
if it's high= adrenal hyperplasia due to ACTH producing tumor (mc lung) then do CT of lungs
If it's Low = adrenal neoplasia Do CT of abdomen
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| elitoki
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C
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